1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, and more particularly to a configuration and a method in which the state of the apparatus is detected and controlled to maintain the apparatus as long a time in a power saving mode as possible to save energy.
2. Description of the Related Art
Among conventional image forming apparatuses such as printers are those equipped with a power saving function. One such apparatus includes a timer and is designed to operate in a power saving mode. A power saving mode is such that if no print job is received for a certain length of time after a print operation is over or the apparatus enters a standby state after a printing operation, a power supply is controlled not to supply high voltage to a fixing unit, drum, belt, operation panel, and LCD or other sections that consume a large power.
In order to shift from the power saving mode back to a print mode, supply of electric power needs to be resumed for preparing a printing operation. Specifically, the temperature of the fixing unit needs to be increased to a normal fixing temperature. The photoconductive drum and transfer belt need to be rotated for cleaning. The operation panel and the display panel such as LCD are again back lit for checking various operations of the apparatus. It takes about a few minutes for a heat roller of the fixing unit to reach the normal fixing temperature.
The apparatus is switched from the power saving mode to the normal printing mode: (1) when the image forming apparatus receives print data from an external apparatus, (2) when a field service engineer closes a cover of the apparatus after repair work, replacement of parts, and (3) when a user closes the cover after replenishment of consumable items or maintenance work.
When the electrophotographic image forming apparatus is turned on, initialization of the apparatus is performed to automatically set up for printing. That is, electric power is supplied to respective sections that require high voltages and high electric power, even though printing is not to be performed immediately after power up.
Some image forming apparatuses incorporate a timer, so that the apparatus is programmed to operate in the power saving mode during a time frame, for example, before normal business hours and lunch time, and after normal business hours in which the apparatus is not used or is used less frequently. Power consumption of the image forming apparatus is thus minimized.
However, it is quite often that in common offices, maintenance work such as replacement of the photoconductive drum and belt and replenishment of toner and paper is carried out before normal business hours, during lunch time, or after business hours, thereby preventing the business efficiency from decreasing.
When maintenance operations are carried out, the user or field service engineer opens the cover of the apparatus, carries out the maintenance work, and then closes the cover again. Even though the apparatus was in the power saving mode prior to the maintenance operation, when the cover is closed after the maintenance operation, the apparatus does not return to the power saving mode but the set-up operation for printing is performed. Thus, the apparatus consumes as much electric power as in the normal printing mode until a predetermined time has elapsed before the apparatus enters the power saving mode. Repetition of such maintenance works shortens the lifetime of the fixing unit, drum, and belt.
Likewise, when the apparatus is turned on, the set-up operation is performed for the apparatus to enter the printing mode even though no printing job is available. This increases power consumption and shortens the life of parts of the apparatus.